The present invention relates generally to forage harvesters having means for processing crop material including maize kernels, these means, for instance, comprising a compressor roll assembly, operable to crack the maize kernels as well as means for processing kernel-free crops such as alfalfa or grass.
A forage harvester is an agricultural machine for comminuting crop material for silage purposes. A harvester is mainly used to harvest grass and maize. With grass-like materials (kernel-free) it is sufficient to slit the crop material, e.g. the stems of the plants are cut to length using a cutter, e.g. a rotating knife drum. When cutting maize the cobs may be slit into smaller size but the majority of the kernels are not broken or cracked. This reduces the nutrient value of the silage crop as the kernels are more-or-less indigestible if not cracked. A cutterhead unit of a forage harvester is used to receive crop material harvested from the field and comminute it into forage which is fed by a blower or accelerator to a temporary container, before being stored and eventually foddered to livestock. In order to facilitate the complete digestion of the crop material, including the maize kernels, the outer skin of the kernels has to be cracked or cut. This can be done by a set of closely adjacent, co-operating compressor rolls with fluted surfaces, installed in front of the blower or accelerator, as shown for example in EP-A-0 177 995 or EP-A-0 664 077.
When chopping maize, forage harvesters make use of the crop processor to crack the kernels in order to obtain a higher nutrient value of the chopped material. In that case the chopped material is thrown by the cutterhead into the crop processor, which processes (cracks) the kernels and transfers the material with sufficient speed into a blower or accelerator, which in its turn ejects the crop into a trailer or container. When chopping other kernel-free crops such as grass or alfalfa, the crop processor is redundant but the rolls may still be worn by the sand/earth in the crop material and damaged by stones therein. It is often removed from the material flow by physically removing it from the machine. In that case the chopped material is thrown immediately by the cutterhead into the blower or accelerator and as such it has to travel over a longer distance without intermediate acceleration. In a number of conditions, especially with light or sticky crops, this can result in poor crop transport from cutterhead to the blower or accelerator due to lack of kinetic energy of the material, causing blockage of the channel between cutterhead and blower or accelerator.
To remove the crop processor from the crop path various methods have been proposed. According to DE 34 07 333 the distance between the rolls is increased to leave a gap between the rolls. Alternatively, the complete crop processor may be removed as known from DE 40 0 888. As yet another alternative, the crop processor may remain in the harvester but means are provided for shifting the crop processor unit between an active position, in which it registers with a duct from the cutterhead and an inactive position, behind the duct. Such a system is known from DE 42 15 696. In DE 195 38 199 it is proposed not to remove the crop processor rolls but to change the direction of crop flow by means of a deflector plate.
All these known solutions have the problem in common that when the crop processor is removed or in an inactive condition the distance from the cutterhead to the blower or crop accelerator is large. Under adverse conditions the long duct between the cutterhead and the blower can become blocked.
DE 196 03 928 proposes to solve this problem with an intermediate impeller. This increases the cost and power consumption of the harvester. In addition, the change requires a change of belt drive which prevents the changeover being carried out from the drive cab. DE 32 34 657 suggests to shift a blower-crop processor combination sideways so that the chopped crop material is either first processed in the crop processor and passed sideways to the blower or, alternatively, passed directly to the blower. The sideways movement moves a pulley for driving the combination to one side thus requiring a belt change. Further, a hatch from the blower has to be removed to provide an inlet for the crop material and a further hatch installed to close the opening left in the crop processor. This means the changeover cannot be carried out from the drive cab. Also it is difficult to prevent some crop material from accumulating in the crop processor when it is in the inactive position.
It is an objective of the present invention to provide a better arrangement for introducing compressor rolls into the stream or removing the same therefrom.
According to the invention, a forage harvester is provided having a crop processor unit for handling crop material including kernels, the forage harvester comprising:
a cutter unit for comminuting said crop material; and
a processing unit which is movable between a first and a second position, said unit comprising:
a crop processor unit disposed adjacent said cutter unit for receiving comminuted crop material from the cutter unit and cracking kernels in the crop material when said processing unit is in said first position, and disposed remote from said cutter unit for letting the comminuted crop material from the cutter unit bypass the crop processor unit when said processing unit is in said second position;
a blower unit for accelerating the processed crop material towards a subsequent handling apparatus, the blower unit being disposed for receiving the processed crop material directly from the crop processor unit when the processing unit is in said first position and for receiving the crop material directly from the cutter unit when the processing unit is in the second position; and
a first drive power connection from a power unit for providing drive power to at least one of the blower unit and the crop processor unit, the power unit being remote from the processing unit,
characterised in that:
said movable processing unit further comprises a frame which is rotatably journalled at one point, said blower unit being mounted to said frame;
said frame being connected to said crop processor unit for moving therewith as the processing unit is moved from the first to the second position; and
said first drive power connection to the at least one of the blower unit and the crop processor unit is operable to remain substantially operational as the processing unit is moved from the first to the second position.
According to a preferred embodiment of the present invention, the power unit may be the prime mover of the harvester or of a tractor which tows the harvester, e.g. a power take-off on the tractor. According to another embodiment of the present invention, the first drive connection is provided by a belt drive. The power unit may be a hydraulic pump or an electric power supply. The first drive connection may be a flexible hydraulic feed from a hydraulic pump or a flexible cable from an electric power supply. The term xe2x80x9csubstantially operationalxe2x80x9d includes minor changes to the drive connection, e.g. re-adjustment of an idler roller but excludes major changes such as changing a belt drive. Preferably, the crop processor unit comprises a compressor roll assembly including a set of closely adjacent co-operating compressor rolls and the blower unit comprises an axle and a suitable blower rotor attached to the axle. Preferably, the axis of the compressor rolls and the axle of the blower unit are parallel but the present invention is not limited thereto. The axis of rotation of the processing unit is preferably parallel to the axis of the compressor rolls.
Preferably, the distance from the output of the cutter unit to the input of the crop processor unit in the first position is about the same as the distance from the output of the cutter unit to the input of the blower unit when the crop processor unit is in the second position. When this is the case there is a reduced chance that comminuted crop material from the cutter units blocks or jams in the chute or duct leading to the blower unit when the crop processor unit is bypassed. Preferably, the blower unit and the crop processor unit are mounted in a frame such that rotation of this frame between the first and second positions is permitted without the removal or disassembly of any drive component of the processing unit, e.g. removal or changing of belt drives or gears. In accordance with one embodiment the crop processor rolls are raised from a low non-crop engaging position to a higher crop engaging position. In the lower position a guide plate may be positioned to isolate the crop processor unit from the blower unit and/or the duct leading to the blower unit.
The forage harvester in accordance with the present invention may be self-propelled or may be towable by a tractor.
According to a further aspect of the present invention, a method is provided of operating a forage harvester, the harvester having a processing unit comprising a crop processor unit for handling crop material including kernels and a blower unit mounted to a frame which is rotatably journalled at one point, the frame being connected to said crop processor unit, the method comprising the steps of:
driving at least one of the crop processor unit and the blower unit in a first position of the processing unit through a first drive power connection from a power unit, so that the crop processor unit receives crop material gathered by the forage harvester and cracks kernels in the crop material;
moving the processing unit to a second position in which the crop material bypasses the crop processor unit and at the same time rotating the frame to move the blower unit towards the cutter unit;
accelerating the processed crop material with the blower unit; and
maintaining the first drive power connection to the at least one of the crop processor unit and the blower unit substantially operational as the processing unit is moved from the first to the second position.
A forage harvester and a method of its operation in accordance with the present invention will now be described in greater detail, by way of example, with reference to the following drawings.